1. Field of the Invention
This invention relates generally to telecommunications, and more particularly, to wireless communications.
2. Description of the Related Art
In a telecommunication system, network planning and an optimal installation and deployment of network infrastructure components is important in order to increase system capacity and maximize network coverage. For example, a plurality of communication nodes, such as base stations with antennas may be geographically distributed across a coverage area. While locations of these communication nodes may be difficult to change, antennas provide mechanisms with which the antenna may be adapted to the various needs of a wireless network. Therefore, antennas play a crucial role in telecommunication systems, such as in digital cellular networks.
However, antennas, among other things, may suffer from different types of mechanical and/or electrical deformations. For example, a cellular antenna may undergo a variety of antenna deformations including warping, modifying the antenna's radiation pattern. An antenna deformation may distort an antenna beam and/or one or more associated lobes in the radiation pattern of a cellular antenna. Some antenna deformations also affect the radiation pattern from a source causing multi-paths and co-channel interference. A cellular antenna may include an array of antenna elements in that a deformed antenna array may alter a phase of an antenna signal and thus antenna lobes (e.g., main, rear and side), resulting in an undesired beam pattern. Accordingly, the cellular antenna may continuously rely upon optimization of coverage area and interference reduction.
To provide desired network coverage, multiple cell sites along with a large number of cells may be deployed. However, as the network capacity and number of cells increase, network throughput and capacity suffers due to cellular antenna deformations. Moreover, as the number of cells increase, antenna deformations may become prime sources of cell-to-cell interference. That is, an antenna deformation may result in a significant degradation in a vital network performance metric in digital cellular systems.
Increasingly light weight antennas are desired for wireless communications. However, this constraint results in a significantly less reinforced or weaker structure for an array antenna of radiating or radar elements. When using such a weaker reinforcement structure, the shape or flatness of the antenna array may be difficult to control. Moreover, as the number of antenna elements increase to provide a narrow antenna beam, the number of errors of phase, which may affect the main lobe of the antenna beam, also increase. In other words, an array environment comprising a large number of antenna elements may fail to focus the main lobe of the antenna beam because the location of each antenna element relative to a deformed aperture of the antenna array.
Referring to FIG. 2, a deformed phased array antenna 200 is illustrated to include an array of antenna elements 205(1-121) distributed over a desired aperture 210. Each antenna element of the array of antenna elements 205(1-121) may receive the same information, i.e., a signal that coherently drives each individual element 205. In this way, all the antenna elements 205(1-121) may radiate in phase. However, as shown in FIG. 2, the desired aperture 210 may deform into a deformed aperture 210a, causing the antenna elements 205(1-121) to alter phase. The deformed aperture 210a provides an output signal from each antenna element that results in interference, causing the deformed phased array antenna 200 to form an antenna beam having a misshaped main lobe. That is, absent a flat surface of the antenna array of the antenna elements 205(1-121), the phased array antenna 100 in a deformed state may provide transmit or receive signals in space causing individual waves to interfere in an undesired way.
However, any undesired shift in the antenna beam may provide a radiation pattern that requires constant adjustment. In particular, for the deformed phased array antenna 200, interference conditions may change even if all the antenna elements 205(1-121) may be connected via a fixed network of transmission lines. For example, the aperture 210 may change to the deformed aperture 210a if the antenna array of the antenna elements 205(1-121) warps because of temperature or other environmental condition(s), which may cause one or more antenna elements 205 to mechanically shift from their original position.
Referring to FIG. 3, a directional radiation pattern 300 is illustrated for the deformed phased array antenna 200 shown in FIG. 2. In the phased array antenna 200, a set of antenna elements 205 located near the center of the antenna array may form the aperture 210a, while the remaining antenna elements 205 may provide the aperture 210. In this way, the curvature of the deformed phased array antenna 200 may cause one or more changes in at least one interference condition. This change in the interference condition may cause the deformed phased array antenna 200 to form a plurality of antenna beams instead of one main lobe. The plurality of side lobes may defocus the antenna beam.